How to use the Sendfox API with PHP

Here's some PHP code that shows you how to use Sendfox's API in PHP.
This specific example shows how to add a new contact to a mailing list, but similar code can be used for all their other API endpoints.

To get the Sendfox list id for the list you want to add a contact to, go to your Sendfox mailing lists and click on the list you want.
You'll see its id in the URL after /lists/